Flotation of minerals



p amino azo benzene,

amino-azo-naphthalene; diamino- .azo-benzene-hydrochlorid (chrysodin dye) UNITED STATES -Parisian" OFFICE.

CLEMENT L. PERKINS, OF PITTS BTIEGHQ PENNSYLVANIA, ASSIGNOR TO METALS RECOVERY COMPANY, OF YORK, N. Y., A CORPORATION" OF MAINE.

FLOTAT ION OF MINERALS.

N 0 Drawing.

This invention relates to the concentra-' tionof minerals, such as sulfid ores and the like, byflotation, and is based upon the discovery that improved results can be obtained by carrying out the flotation operation with the addition to the ore or mineral pulp of organic nitrogen compounds containing two nitrogen atoms joined to each other, and more particularly azoor diazo-compounds, such as,-for example, diazo-amino-toluene,

etc.

Among the azo and diazo-compounds which can thus be used may be mentioned thefollowing :-diazo-amino-benzene (C H .N:N 'NH.C H .cliazo-amino-p-tolu ene; benzene-diazo-amino-p-toluene; formazyl-azo-benzene '(C H .N:N) C :N.NHC H azo-benzene ('C H .N-N.C H azonaphthalene (alpha alpha derivative);

C H .N:N.C H L);

benzene-azo-phenol (C H .N:N.C H O I); toluene-azo-resorcino; benzene-azo-a-napththol, etc. Among'th compounds mentioned it will be'notedthatthere are included azocompounds, amino-azo-compounds, diazoamino compounds, and oxy-azo compounds or azo phenols. These various compounds may be added either in the form of the free base, or in the form of salts thereof with acid, for example, in the form of the hydrochlorid or sulfate.

.Among the various compounds above men- .tioned, the diazo-amino com'poun'ds appear to be the most valuable in promotin the flo-- tation' operation, for the reason at they have particularly valuable propertles as col lecting agents; that is, as agents which cause a very material increase in the recovery off .mineral when .used in connection with a Specification of Letters Patent Patented Jan. 4, 1921.

Application filedll'uly21, 1919. Serial No. 312,248.

ticularly as collecting agents. The Sudan dyes, which are also oxy-azo compounds, for example, benzene-azo-b-naphthol, xyleneazo-b-naphthol, benzene-azo-benzene-azo-bnaphthol, a-naphthalene-azo-a-naphthol,the

sodium salt of sulfo-benzene azo-benzeneazo-b-naphthol-sulfonic acid, etc., show a se lective action for sulfid minerals, although these dyes proved less advantageous than the amino-azo, (llHZO-QIIIIIIO and oxy-azo compounds above referred to.

In-my companion application, Serial No.

have described and claimed certain improvements in the flotation of minerals and the like, with the aid of hydrazins and hydrazin derivatives. Accordingly, in the present application I do not claim specifically the improvements in which the hydrazins are. employed, but I nevertheless intend the present caseto begeneric to the invention of said companion application, and the more comprehe'nsive claims of the present application to include the process of said companion application. That is, the more comprehen sive aspects of the present invention relate to the process in which the flotation operation is carried out with the addition to the ore or mineral pulp of nitrogen compounds containing two nitrogen atoms joined to each case of the hydrazin compounds, or by a double bond, as in the case of the azo and diazo compounds; inasmuch as 1t is new,

in so far as I am aware, to carry out the flotation operation with the addition to the ore or mineral pulp of mtrogeneous compoundsof this character, that is, nitrogenous compounds of the character of azo, diazo, hydrazo, hydrazin, etc., compounds which contain within their molecules the characteristic nitrogen groups of these compounds. The specific claims ofthe present application are directed to the 2120-, and diazo-compounds which contain the doubly bound nitrogen atoms, as distinguished from the ,hydrazin compoundsof said companion a plication, which have but a single linkage between the two nitrogen atoms.

- The azo-and-diazo compounds can be in corporated with the ore or mineral pulp any suitable manner, Which Will lnsure. thelr uniform incorporation and dlssemmation throughout the pulp. They may thus be incorpora-ted by grinding in the tube mill in pulp, or they may in which the ore is itself ground, or theymay be dissolved in an organic solvent therefor and the resulting solution added to the ore ested in water and the resulting product then added to the ore pulp,

After the azo or diazo compound,'either alone or with other flotation agent or agents, has been thoroughly and uniformly distributed throughout the ore or mineral pulp, the resulting mixture is subjected to a flotation operation, as in anordinary Callow cell, or in apparatus where the air is incorporated in the ore pulp by mechanical agitation.

It is of advantage in many cases to add to the ore pulp a small amount of alkali, sufficient to give the ore pulp adistinct alkaline reaction. The alkali may be added both when the compound is added in the form of the free base, and when it is added in the form of a salt. 'When a salt of the base is employed, he alkali may act upon it, to a greater or less extent, to set free the free base, but the action of the alkali appears to be an action upon the ore pulp, or upon the mineral constituent, rather than or in addition to its action upon the salt of the compound used, although I do not desire to limit myself" by any theoretical explanation of what the action of the added alkali may be in promoting the flotation operation. A

similar improvement has been noted both when the alkalihas been used with the free base and when used with salts of the base. The alkali may be caustic alkali, such as sodium hydrate,- or an alkaline salt, such .as sodium carbonate, or even lime or cal-- cium oxid or hydrate can be used.

The amount of the azo or diazo compound added may vary somewhat, and may be. as little as one-fifth or one-fourth of a pound perton of ore; (that is, calculated on-the weight of the ore and not of. the ore pulp), but larger amounts may, with advantage, be

used, particularly where thedzompound is difficult to uniformly disseminate throughout the ore pulp, and as much as one or one and one-half pounds perton of ore, or even more, can be used. r

The azo and diazo compounds have proven to be of particular value in the flotation of copper sulfid ores having a siliceous gangue and containing their fioatable 0r sulfid copper in the form of a mixture of chalcocite and chalcopyrite, that is, so-called porphyry ores, such as those of the Utah Copper Company. In general, treatment of the orewith alkalis, such as sodium hydrate or lime, gives improved results. In fact, the alkalis themselves seem to have a valuable effect upon the ores in improving the flotation thereof, and

the same is true for a number of similar ores. I When alkalis are used, it is desirable to give them an appreciable time of "contact with the ore pulp before subjecting the latsome cascsfirst be di 1. D' azo-amino-bonzene 2. Diazo-ammo-p-toluonc ter to flotation. When possible, it is preferable to add the alkalis in the grinding mill, so that they will be present during the grinding operation.

The following more specific description will further illustrate the invention.

500 parts by weight of the ore, previously crushed to pass a 30 mesh sieve, were placed n the pebble mill, together with the indicated amount of the diazo-amino compound, 250 parts of water, and sodium hydroxid equivalent to two pounds per ton of dry ore, or, in place of the sodium hydroxid, lime in about the same proportion. After the grinding operation, the charge was transferred toa (allow rougher cell and subjected to flotation with the addition of a small fraction of one pound of terpineol per ton of dry ore, or, instead of terpineol, pin oil, or other frothingagent. Terpineol has very little if any collecting power, and functions almost entirely as a frothing agent.

The following are results obtained with certain of the above diazo compounds when used on Utah ore in amounts equal to about one-fifth of a pound per ton of ore:

. Benzene-diazo-amino'toluene The diazo-amino compounds are exceedingly powerful collecting agents, even when used in mere traces; for example, as little as one-thirtieth of a pound of diazoamino benzene per ton of ore has been found to be sufiicient as a collecting agent to give almost maximum results with Utah ore, when used with a small amount of a frothing agent. In general, a frothing agent must be used with these compounds, inasmuch as they have little or no frothing properties themselves, as above pointed out. These compounds are very difi'icultly soluble solids and are very stable in the air. Continued boiling with water results in their decomposition. They may be dissolved, for flotation. purposes, in organic solvents, such as alco-. hol, anilin, dimethyl-anilin, xylidin, etc. Prolonged heating with other amins may result in chemical changes which reduce the effectiveness of the mixture. Where a solution-of one of these compounds in an organic solvent is prepared, it may be added either to the pulp in the grinding mill, or to the ground pulp immediately before flotation. Organic solvents may be properly chosen so as to furnish frothing power to supplement the valuable collecting pro erties of the diazo and azo compounds. he diazo-- amino compounds may also be incorporated in the usual oil mixtures, such as are employed in flotation, and thereby introduced into the pulp, and they will exert a marked improvement in the flotation results obtained with most,- if not all, such oil mixtures. The procedure which I recommend, when it is possible, is to add the reagent in very finely pulverized dry form to the ore pulp in the grinding mill. Frothing agents,

such as pine oil, hardwood oil, and various other frothing agents, may be added at the same point,or just previous to flotation, as desired.

The diazo-amino compounds, as above noted, are excellent collecting agents, and this is true as well of the diazo-amino-ptoluene and the benzene diazo-amino-ptoluene, as ofthe.diazo-amino-benzene. The para-amino-azo-benzene and the aminoazo-naphthalene, as Well as certain of the oxy-azo compounds, are likewise good collecting agents, but I consider them less valuable than the diazo-amino compounds.

Improved results have alsobeen obtained in the flotation of zinc-lead ores such. as those of the Butte and Superior Company. Good results were thus obtained when the diazo-amino compound was ground with the neutral ore pulp, but better results were obtained when copper sulfate and sulfuric acid, in the proportion of one pound of each per ton of dry ore, were also used. A small amount of a suitable frothing agent, as above noted, should also be used.

Itis characteristic of the invention that the froth obtained is readily broken up,

while a relatively clean concentrate and high recovery can, nevertheless, be obtained. The azo or diazo compound can, moreover, sometlmes be recovered, so that it is avail:

able for use in the treatment of further amounts of ore, for example, by recovering the circuit water from the concentrates, and

even that from the tailings, and returning.

' each other, and subjecting the resulting mixture to a flotation operation; substantially as described.

.2. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small amount of an organic nitrogen compound containing two nitrogen atoms joined to each other, to ether with a flotation agent having marke frothing properties, and sub jecting the resulting mixture to a flotation operation; substantially as described.

3. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small amount of an organic nitrogen compound containing two nitrogen atoms joined to each other, together with sufficientalkali to give to the ore pulp a distinct alkaline reaction, and subjecting the re'sultingmixture to a flotation operation; substantially as described.

4. The method of eflecting the concentration of minerals by flotation, which con1 prises adding to the mineral pulp a small amount of an organic nitrogen compound containing two nitrogen atoms joined to each other, together with a flotation agent having marked frothing properties and suflicient alkali to give to the ore pulp a distinct alka line reaction; and subjecting the resulting 7 mixture to a flotation operation; substantially as described.

5. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small amount of an organic nitrogen compound containing two nitrogen atoms joined to each other by a double bond, andsubjecting the resulting mixture to a flotation opera- "tion; substantially as described.

6. The method of eifecting the concentration of minerals by flotation, which comprises adding to the mineral" pulp a small. amount of 'an organic nitrogen compound containing'two nitrogen atoms joined to each other by a double bond, together with a flotation agent having marked ,frothing properties, and subjecting the resulting mixture to a flotation operation; substantially as described.

7 7. The method ofefl'ecting the concentration of minerals by flotation, which comprises addingto the mineral 'ulp a small amount'of an azo compound e., an aromatic compound containing the -N:N- group), and subjecting the resulting mixture to a flotation operation; substantially as described.

8. The method of effecting the concentration ofminerals by flotation, which comprises adding to the mineral pulp a small amount of an organic diazo-amino compound, and subjecting the resulting mixture to a flotation operation; substantially as described. j

9. The method of effecting the concentra tion of minerals by flotation, which coinprises adding to the mineral pulp a small amount of diazo-amino-toluene, and subjecting the resulting mixture to a flotation operation; substantially as described.

In testimony whereof I aflix my signature.

CLEMENT L. PERKINS. 

